Allenics for inhibiting corrosion



United States Patent 3,551,348 ALLENICS FOR INHIBITING CORROSION ArthurH. Du Rose, Richmond Heights, Ohio, assignor to Kewanee Oil Company,Bryn Mawr, Pa., a corporation of Delaware N0 Drawing. Filed Sept. 21,1967, Ser. No. 669,400 Int. Cl. C23f 11/10 US. Cl. 252-388 10 ClaimsABSTRACT OF THE DISCLOSURE This invention covers the use of alleniccompounds as corrosion inhibitors in acidic aqueous solutions to protectferrous, zinc and aluminum containing materials. The concentration canrange from about 0.005 to about 4 grams per liter.

This invention relates to a method for inhibiting corrosion of ferrous,zinc and aluminum metal and alloys, More specifically it concerns amethod for inhibiting corrosion of such metals in aqueous acidenvironments by use of certain allenic compounds. It also includes theenhancement of the inhibiting power of allenic compounds by use ofwetting agents or low concentration of iodides.

Allenic compounds while frequently mentioned in the literature, arestill somewhat of a rarity in commercial quantities or commercial use.However it is known that their reactions are similar to those ofolefins, the two ethylenic linkages acting independently of each otherand addition at double bonds is subject to the influences of othergroups as are observed with other ethylenic compounds. The most simpleallenic compound is allene, CH C=CH a gas at ordinary temperatures andtherefore not practical as an inhibitor.

It is well known that metals such as steel, zinc and aluminum when incontact with water and especially acidic water are slowly to rapidlycorroded. In some cases this is the desired effect but in most cases itis desirable to prevent or retard corrosion.

Therefore a wide variety of compounds that retard corrosion have beenuses as inhibitors in water and acidic solutions. Such known inhibitorsinclude; labile organic sulfur compounds such as thiourea, dipropargylsulfide and mercapto compounds; nitrogen compounds such as polyamines,decylamine and piperidinium 3,5 dinitrobenzoate; phosphorous compoundssuch as alkyl phosphate esters and alkyl selenophosphates; aldehydes;and inorganic compounds such as nitrites and chromates are also used. Itis also known that compounds containing the single double bond or triplebond may be good inhibitors. Acetylenic compounds such as propargylalcohol and 2- methyl-3-butyn-2 01 are especially good inhibitors. It iswell known in the art that anionic, cationic, nonionic, and amphotericwetting agents will frequently enhance the effectiveness of aninhibitor. This is also true for small concentrations of halides,particularly iodide.

Inhibitors are used in metal cleaning formulations, in acid pickling,where it is desired to remove scale and rust with but little attack onthe basis metal, in hydraulic fluids, in lubricating oil emulsions, inmetal paints and also as vapor inhibitors in packaging.

The mechanism by which an inhibitor functions has been given much study.In general, it has been concluded that the inhibitor adsorbs, usually bychemisorption, on the surface of the metal. The adsorption may takeplace on anodic or cathodic sites or possibly, in some cases, form analmost complete adsorbed film over the surface atoms of the metal.

This has led to various types of electrochemical polarizationmeasurements to determine the extent of probable corrosion inhibitionand to determine whether the corrosion is under cathodic or anodiccontrol. Another method to evaluate the degree of corrosion is tomeasure the volume of hydrogen evolved when the metal is exposed to anacidic solution for a given period of time.

The method which is usually employed and which is almost always used tocorrelate with the polarization studies is the simple weight lossmethod. In this method two coupons of metal of given area are exposed tothe same acidic solutions, one solution containing a small concentrationof inhibitor and the other no inhibitor. The tests are performed underthe same condition of temperature, time and agitation. The efficiency ofinhibition is then calculated as AwAw where Aw and Aw are the metalweight losses for the coupons in the uninhibited and inhibited solutionrespectively. This is the method we have chosen to show theeffectiveness of allenic compounds as inhibitors.

In accordance with the present invention it has been found that thecumulative effect of adjacent double bonds as found in allenic compoundsincluding cumulene makes such compounds considerably more effective thansimple olefins.

The compounds found to be particularly suitable as inhibitors in acidsolutions are defined by the formula:

R is hydrogen or an alkyl radical of 1-4 carbon atoms,

or two Rs can be aliphatic hydrocarbon divalent radicals joined to forma six-membered cycloaliphatic ring With the carbon of the formula,

R is hydrogen or an alkyl radical of 1-4 carbon atoms,

R is a divalent saturated aliphatic hydrocarbon radical of 26 carbonatoms,

Ar is phenylene, naphthylene, diphenylene or an alkylene derivativehaving 14 carbon atoms in the alkylene group, and

n is an integer having a value of 1 to 10.

The concentration of the allenics of the instant invention required toeffect corrosion inhibition vary according to the conditions of use andthe particular allenic used. However, concentrations as low as 0.005gram per liter have been effective to substantially inhibit corrosion ofiron, zinc and aluminum. The only upper limit on allenic concentrationin the practice of the instant invention is the solubility limit of theparticular allenic used or its vapor saturation point when used in anon-aqueous corrosion inhibition situation. In no case, however, is anyadditional corrosion inhibition realized by exceeding in an allenicconcentration of 4 grams per liter.

Allenic compounds defined by the above generic for- 3 mula as beingsuitable in the practice of this invention include but are not limitedto the following:

4 (33) CH2 C CHCH2N(C2H5)3Cl (34) cn cn c cncn iv (CH Br (35 CH =C=CHCH(OCH CH 0H 31) CIIFC C(C1I3)CII2(OCIIZCII)301I 01-13 37 CH =C=CHCH OCHCH OCH CH CH CH OH ou on (3a) tlL C ClI-U ou ofi 31) on clcn-c 11 NHCIIgCII:

crncrrg (40) ClIi-ClI C CII-CH nit-1101 The invention is bestillustrated by the following examples. These examples are given by wayof illustration and are not intended in any way to restrict the scope ofthe invention nor the manner in which it may be practiced.

EXAMPLE I Low carbon steel panels 0.75" X 6" are placed in a large testtube containing 8% v./v. of concentrated H 50 and a equal volume ofconcentrated hydrochloric acid and 0.2% of the inhibitor. Controls arealso used in which the corrosive medium contains no inhibitor. Theimmersion time is 6 hours and the temperature is 32 C. Methyl butynol, acommonly used acetylenic inhibitor is used for comparison. The panelsare weighed before and after the corrosion period and the inhibitionefliciency calculated as previously described. Table 2 gives theresults.

TABLE II ElIIClGlICY, Comprl. No. Inhibitor percent 1 Methyl butynol(2-methyl-3-butyn2ol). 94. 6 2,2-diethyl-penta-BAdiene-l-al.. 97. 2l,2-butadiene-4-0l 96.2 t 1,2-butediene-4-ol ethylene oxide adduct..."95. 0 l-allenyl-l-iormyl-cyclohex-3-ene U9. 1 i2,Z-dimethyl-penta-3,4dien-l-al 94. 3 2methyl-2,3-butadienyltrirnethylammo- 85. 3

nium chloride. l(pdimethylaminophenyl)-2,2dimetl1yl- 96. 5

penta-3,4-dienol HCl. l-allunyl-Lcarbinol-cyclohex-3-ene 94. 52,2-di1nethylpenta3,4-dienol 88. 7 2,2,5-trimethylhexa-lidienal 74. 72,3-butadienoic acid J2. 0

EXAMPLE II In this example the effect of concentration of the inhibitoris demonstrated. The conditions were similar to those of Example Iexcept that 20% hydrochloric acid was used at room temperature and thecorrosion period was 3.5 hours. The following table shows that very lowconcentrations may be used.

TABLE III Inhibitor.

percent Ellit-iency,

Panel v.1'v. Inhibitor percent 0. 05 Methyl butynol 90. l

0.10.... do i i i 98.5

EXAMPLE III Here is shown the effect of methyl pentynol and threeallenic inhibitors on the corrosion of 0.032" thick A.C.S. reagent gradezinc in 5% v./v. sulfuric acid. The time was 2 hours, inhibitorconcentration 0.2%, and performed at room temperature. The alleneinhibitor numbers in Table IV as well as in those exanmles which 5follow refer to the numbers in Table II. It will be noticed that theaddition of the wetting agent in the case of panel 5C slightly increasedthe efliciency of inhibitor No.2.

TABLE IV Panel Inhibitor percent l-C Methyl pentynol 84. 2

2-C Allene #2 (2,2-diethylpenta-3,4-diene-l-al) 95. 8 3-0 Allene #5(l-allenyl-l-fonnyl-eyclo-H-ene) 95. 4 4-0 Allene #11(2,2,5-trirnethylhexa-3,4-dienal) 94. 5 5-0 Allene #2 (see above panel2-C plus 0.1% v./v. Surt- 96 5 ynol (a surface active agent).

EXAMPLE IV TABLE V Efficiency, Panel Inhibitor percent 1-BMethylpentynol (3-rnethyl-1-pentyl-3-ol) 78. 2-13 Allene #2(2,2-diethyl-penta-3,4-dien-1-al) 66. 8 3-13 Allene #11(2,2,5-trimethylhexa-3,4-dienal) 57. 3

EXAMPLE V Aluminum (alloy 6061) is immersed in sodium hydroxide at roomtemperature for 65 minutes. Allene No. 5 'was used at 0.1%. Theefficiency was only 12% indicating that the allenic compounds do nothave much promise as inhibitors for aluminum in alkaline solutions.

EXAMPLE VI Two steel strips are immersed in separate solutionscontaining 4% by volume sulfuric acid plus 0.2% by volume hydrochloricacid. One of the solutions contains 0.1% by Weight of Allene No. 7. Theinhibitor efliciency after 2 hours immersion is 98.2%.

EXAMPLE VII Steel strips were immersed in 3M H 50 at room temperaturefor 4 hours. The efficiency of the inhibitor without and with theaddition of 7 10 M K1 is shown in Table VI.

TABLE VI Inhibitor and concentration: Percent efficiency NO. 11 at 0.05%58.5 N0. 11 at 0.05%, plus KI 99.820 No. 5 at 0.01% 80.6 NO. 5 at 0.01%,plus KI 99.846

EXAMPLE VIII Here is compared the eifect of an allene with a compoundcontaining a single double bond and also with a compound containing twononadjacent double bonds. Steel panels were immersed in 20% hydrochloricacid for 22 hours at room temperature. The inhibitor concentration was0.1% and the efficiencies are shown in Table VII.

TABLE VII Efficiency, Inhibitor percent Panel:

1-D Allene #5 98. 5 2-D Methyl butenol (3-methyl-1-butene-3-ol) 58. 73-D 2,5-dimethyl-l,5-hexadienc-3-ol 58. 4

EXAMPLE IX The following test was performed as an indicative example ofvapor inhibition. Several layers of filter paper were layed on thebottom of three 1 liter tall form beakers. In all cases the filter paperwas saturated with water. About 0.5 g. of Allene No. 2 was added to thewet filter paper in one beaker and 0.5 g. of Allene No. 3 (see ExampleI) to that in another beaker. No inhibitor was added to the thirdbeaker. Clean steel panels were then placed upright in the three beakersand these placed in a laboratory where the atmosphere was acidic andhumid for four weeks. Once a week the filter papers were rewetted withwater or water plus inhibitor. At the end of four weeks the steel in thebeaker containing no inhibitor had become tarnished with yellow rustwhile the panels in the beakers containing the inhibitors wererelatively tarnish-free.

From the previous examples, it is obvious that the effectiveness ofallenic compounds as inhibitors can be equal or greater than that ofacetylenic compounds. In this respect they resemble the acetyleniccompound more than they do simple olefins or conjugated diolefins. Italso appears that those allenes with a terminal double bond are moreeffective as inhibitors for steel than those which do not have theterminal double bond. In general this is also true for olefins andacetylenic compounds.

Due to the volatility of some of the allenic alcohols and aldehydes atelevated temperatures, it is generally advisable that the inhibitorcontaining solution be held at a temperature of less than 130 F. Thisrestriction of course is not necessary for the allenic amines which formnonvolatile salts.

Allenic compounds used in the practice of this invention can be preparedby various methods taught in the prior art, including British Pat.971,751; Bailey & Pfeifer, J. Org. Chem., 20, 1337-41 (1955); Eglintonet al., J. Chem. So., 3197-3200 (1954). Typical procedures are givenbelow for various typical compounds.

1-a1lyl-2,2-demethyl-3 ,4-pentadienal A solution containing 0.15 mole ofallylmagnesium bromide in 250 ml. of ether is added dropwise withcooling to a solution of 16.5 g. (0.15 mole) of 2,2-dim-ethyl-3,4-pentadienal in 30 ml. of ether. After the reaction is complete themixture is shaken with dilute hydrochloric acid. The ether phase isseparated, Washed with fresh water and dried over sodium sulfate. Uponevaporation of the ether and distillation of the residue, 8.0 g. ofproduct is collected which boils at 801 C. at 10 mm. Hg. Infraredanalysis shows strong adsorption at 5.1 microns, which is characteristicof the allenic group, and strong adsorptions for hydroxyl and allylgroups.

1- (p-dimethylaminophenyl -2,2-dimethyl-3,4- pentadienol An etherealsolution containing 0.1 mole of p-dimethylaminophenyl lithium is addedover a 0.5 hour period, at ice bath temperature, to an ethereal solutionof 11.0 g. (0.1 mole) of 2,2-dimethyl-3,4-pentadenol. After the reactionis complete the mixture is cautiously hydrolyzed with an excess ofwater. The ether phase is separated and extracted with dilutehydrochloric acid. The combined extracts are washed with fresh ether andthen neutralized with dilute sodium hydroxide. The product is extractedseveral times with ether and the combined extracts are dried over sodiumsulfate. The product is precipitated from ether solution as thehydrochloric salt with anhydrous hydrogen chloride. A white solid, 15.0g., is collected. Infrared analysis shows strong allenic absorption at5.1 microns, and strong absorptions for hydroxyl, amino and phenylgroups.

l-formyl-1-allenylcyclohexene-3 A mixture of 23.0 g. (0.41 mole) ofpropargyl alcohol, 45.3 g. (0.41 mole) of 1-formylcyclohexene-3, 0.1 g.of hydroquinone and 0.1 g. of p-toluene sulfonic acid in ml. of benzeneis heated at reflux for 5 hours. The water of reaction is collected in aDean-Stark trap. Fractionation of the mixture affords 22.0 g. of productboiling at 7 groups.

71 C. at 3 mm. Hg. Infrared analysis shows strong absorption for theallenyl, aldehyde and cyclohexene groups.

l-hydroxymethyll-allenylcyclohexene-3 To a solution of 10.3 g. (0.07mole) of l-formyl-lallenylcyclohexene-3 and 7.0 ml. of 40% formaldehydesolution in 25 ml. of methanol is added 8.4 g. of 50% sodium hydroxidesolution over 15 minutes at 35-50 C. The mixture is then heated at 60 C.for 3 hours and poured into 300 ml. of water. The mixture is extractedwith three 50 ml. portions of benzene. The combined extracts are driedover sodium sulfate and distilled. By this procedure, 6.5 g. of product,boiling at 95-6 C. at 3 mm. Hg is collected. The infrared analysis showsstrong absorptions for the allenic, hydroxyl and cyclohexenyl3,6-dioxa-8,9-decadien-l-ol A mixture of 1.0 g. of powdered potassiumhydroxide and 40 ml. of isopropanol is stirred at reflux until thesolids are dissolved. The solution is cooled at 25 C. and 10.0 g. (0.143mole) of 2,3-butadiene-1-ol is added. With agitation, 13.2 g. (0.3 mole)of ethylene oxide is passed into the solution over a 30 minute period.The reaction temperature is maintained at 25-35 C. by intermittentcooling. After the addition is complete the mixture is stirred at 40-50C. for 1 hour and then at 30 C. for an additional 2 hours. The catalystis neutralized with hydrochloric acid and the mixture is filteredthrough a bed of Filter Cel. The isopropanol and nnreacted 2,3-butadiene-l-ol are distilled from the mixture to a maxi mum pottemperature of 80 C. at 10 mm. Hg. A dark orange, water soluble oil,19.5 g., is obtained. Infrared analysis indicates strong absorption forthe allenic, ether, and hydroxyl groups.

I claim:

1. A corrosion inhibited aqueous acid solution containing an effectivecorrosion inhibiting amount of an allenic compound of the formula R, Rand R are selected from the group consisting of hydrogen and methyl,

X is selected from the group consisting of -CHO;

R is selected from the group consisting of hydrogen or an alkyl radicalof l-4 carbon atoms, or two such R s can be aliphatic hydrocarbondivalent radicals joined to form a six-membered cycloaliphatic ring withthe carbon of the formula,

R is selected from the group consisting of hydrogen and an alkyl radicalof 1-4 carbon atoms,

R is a divalent saturated aliphatic hydrocarbon radical of 26 carbonatoms,

Ar is selected from the group consisting of phenylene, naphthylene,diphenylene or an alkylene having 1-4 carbon atoms, and

n is an integer of from 1-10.

2. A corrosion inhibited aqueous acid solution as stated in claim 1wherein said allenic compound is present in a concentration of betweenabout 0.005 and 4 grams per liter of solution.

3. A corrosion inhibited aqueous acid solution containing an effectivecorrosion inhibiting amount of 2.2-dicthylpenta-3,4-diene-1-al.

4. A corrosion inhibited aqueous acid solution contain R u-c:C:( X

wherein R. R and R are selected from the group consisting of hydrogenand methyl, X is selected from the group consisting of --CHO;

-COOH; --CH OH; -C(R CHO;

R is selected from the group consisting of hydrogen or an alkyl radicalof l-4 carbon atoms, or two such R s can be aliphatic hydrocarbondivalent radicals joined to form a six-membered cycloaliphatic ring withthe carbon of the formula R is selected from the group consisting ofhydrogen an an alkyl radical of l-4 carbon atoms,

R is a divalent saturated aliphatic hydrocarbon radical of 2-6 carbonatoms,

Ar is selected from the group consisting of phenylene, naphthylene,diphenylene or an alkylene having 1-4 carbon atoms, and

n is an integer from 1l0.

7. A method of inhibiting corrosion of ferrous, zinc or aluminumcontaining materials in acidic aqueous solutions which comprisesdissolving in said aqueous solutions between about 0.005 and 4 grams perliter of 2,2-diethyl- 3,4-diene-l-al.

8. A method of inhibiting corrosion of ferrous, Zinc or aluminumcontaining materials in acidic aqueous solutions which comprisesdissolving in said aqueous solutions between about 0.005 and 4 grams perliter of l-allenyl-lformyl-cyclohex-B-ene.

9. A method of inhibiting corrosion of ferrous, zinc or aluminumcontaining materials in acidic aqueous solutions which comprisesdissolving in said aqueous solutions between about 0.005 and 4 grams perliter of 2,3-butadienoic acid.

10. A method of inhibiting corrosion or tarnishing of ferrous, zinc oraluminum containing materials in a corrosive atmosphere contacting saidmetal containing materials with a corrosion inhibiting amount of anallenic compound in a vapor phase, said allenic compound being of theformula wherein R, R and R are selected from the group consisting ofhydrogen and methyl, X is selected from the group consisting of -CHO;

-COOH; CH OH; -C(R CHO;

C(R COOH;

-C(R CH OH;

C(lifiJllAl'NUfih; '(u* 11o.u,N; C(lt") CllC;ll N on on on 9 10 --C(RN(R Cl; C(R (OR ),,OH; C H N; naphthylene, diphenylene or an alkylenehaving 1-4 carbon atoms, and and C H N, n is an integer from 1-10. R isselected from the group consisting of hydrogen or an alkyl radical of1-4 carbon atoms, or two such 5 References Clted R s can be aliphatichydrocarbon divalent radicals UNITED STATES PATENTS jOined t0 fOrIn a.siX-Inembered CyClOaliphatiC ring Jacobs et a1.

with the carbon of the formula, R is selected from the group consistingof hydrogen RICHARD D. LOVERING, Primary Examiner an an alkyl radical of1-4 carbon atoms, 10 R is a divalent saturated aliphatic hydrocarbonradical GLUCK Asslstant Exammer of 2-6 carbon atoms, s, L

Ar is selected from the group consisting of phenylene, 252 143 396

